Dual action sander

ABSTRACT

A dual action sander includes a housing, a motor shaft balancer, a balancer shaft, an engaging member and a control rod unit. The motor shaft balancer is disposed in the housing, and is rotatable about a first axis. The control rod unit is movable along the first axis between a locked position, where the balancer shaft is not permitted to rotate about a second axis that is parallel to and spaced apart from the first axis, and an unlocked position, where the balancer shaft is permitted to rotate about the second axis. The engaging member is mounted to one of the balancer shaft and the control rod unit, and is engaged with the other one of the balancer shaft and the control rod unit when the control rod unit is in the locked position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority of Taiwanese Patent Application No. 107136333, filed on Oct. 16, 2018.

FIELD

The disclosure relates to a sander, and more particularly to a dual action sander.

BACKGROUND

Referring to FIGS. 1 and 2, U.S. Pat. No. 5,823,862 A discloses a conventional dual action sander 1 that includes a housing 11, a motor 12, a motor shaft balancer 13, a bearing 14, a balancer shaft 15, and a latch pin 16.

The motor 12 is mounted in the housing 11. The motor shaft balancer 13 is disposed in the housing 11, is mounted to the motor 12 along a central axis (CL) to be drivable by the motor 12 to rotate about the central axis (CL) relative to the housing 11, and defines a receiving space 130 therein. The bearing 14 is fixedly disposed in the receiving space 130 of the motor shaft balancer 13, surrounds a rotating axis (RL) which is parallel to and spaced apart from the central axis (CL), and is sleeved on the balancer shaft 15. The balancer shaft 15 is rotatable about the rotating axis (RL) relative to the motor shaft balancer 13, and is formed with a recess 151 in a top surface thereof. The latch pin 16 movably extends through the motor shaft balancer 13 along the central axis (CL), and is convertible relative to the motor shaft balancer 13 between a locked position and an unlocked position.

When the latch pin 16 is in the locked position, it is engaged with the recess 151 of the balancer shaft 15 so as to prevent the balancer shaft 15 from rotating about the rotating axis (RL) relative to the motor shaft balancer 13. When the latch pin 16 is in the unlocked position, it is separated from the recess 151 of the balancer shaft 15 so that the balancer shaft 15 can rotate about the rotating axis (RL) relative to the motor shaft balancer 13. By virtue of the configuration of the latch pin 16, a user may operate the conventional dual action sander 1 for either heavy stock removal or fine polishing, in order to meet different requirements.

A manufacturer of the conventional dual action sander 1 may wish to increase a sanding or cutting force of the conventional dual action sander 1 by increasing a distance between the central and rotating axes (CL, RL). However, increasing the distance between the central and rotating axes (CL, RL) may cause the latch pin 16 and the recess 151 of the balancer shaft 15 to not be properly engaged when the latch pin 16 is in the locked position.

SUMMARY

Therefore, the object of the disclosure is to provide a dual action sander that can alleviate the drawback of the prior art.

According to the disclosure, a dual action sander includes a housing, a rotating unit, a driving unit, a balancer shaft, an engaging member and a control rod unit.

The rotating unit is disposed in the housing, and includes a motor shaft balancer that is rotatable relative to the housing about a first axis, and that has a balancer portion and a motor shaft portion. The balancer portion defines a receiving space that extends along a second axis being parallel to and spaced apart from the first axis. The motor shaft portion extends from the balancer portion along the first axis, and defines a through hole that extends along the first axis and that is spatially communicated with the receiving space.

The driving unit is disposed in the housing for driving the rotation of the motor shaft balancer about the first axis.

The balancer shaft extends into the receiving space of the motor shaft balancer, and is co-rotatable with the motor shaft balancer about the first axis.

The control rod unit extends along the first axis through the through hole of the motor shaft portion of the motor shaft balancer, and is movable along the first axis between a locked position, where the control rod unit is secured to the balancer shaft so that the balancer shaft is not permitted to rotate about the second axis during co-rotation of the motor shaft balancer and the balancer shaft, and an unlocked position, where the control rod unit is separated from the balancer shaft so that the balancer shaft is permitted to rotate about the second axis during the co-rotation of the motor shaft balancer and the balancer shaft.

The engaging member is mounted to one of the balancer shaft and the control rod unit, and is engaged with the other one of the balancer shaft and the control rod unit when the control rod unit is in the locked position.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the disclosure will become apparent in the following detailed description of the embodiments with reference to the accompanying drawings, of which:

FIG. 1 is an exploded schematic and perspective view of a conventional dual action sander disclosed in U.S. Pat. No. 5,823,862 A;

FIG. 2 is a fragmentary and partly sectional view of the conventional dual action sander;

FIG. 3 is a perspective view of a first embodiment of a dual action sander according to the disclosure;

FIG. 4 is an exploded perspective view of the first embodiment;

FIG. 5 is an exploded perspective view of an engaging member and a balancer shaft of the first embodiment;

FIG. 6 is a view similar to FIG. 5, illustrating a variation of the engaging member and the balancer shaft of the first embodiment;

FIG. 7 is a fragmentary sectional view taken along line VII-VII of FIG. 3, illustrating a control rod unit of the first embodiment in an unlocked position;

FIG. 8 is a view similar to FIG. 7, illustrating the control rod unit in a locked position and engaged with the balancer shaft;

FIG. 9 is an exploded perspective view of a second embodiment of the dual action sander according to the disclosure, illustrating a rotating unit, the control rod unit, the engaging member and the balancer shaft of the second embodiment;

FIG. 10 is a fragmentary sectional view of the second embodiment, illustrating the engaging member mounted to the control rod unit, and the control rod unit in the unlocked position;

FIG. 11 is a view similar to FIG. 10, illustrating the control rod unit in the locked position and engaged with the balancer shaft;

FIG. 12 is an exploded perspective view of a third embodiment of the dual action sander according to the disclosure, illustrating the rotating unit, the control rod unit, the engaging member and the balancer shaft of the third embodiment;

FIG. 13 is fragmentary sectional view of the third embodiment, illustrating the control rod unit extending through the engaging member, and the control rod unit in the unlocked position; and

FIG. 14 is a view similar to FIG. 13, illustrating the control rod unit in the locked position and engaged with the balancer shaft.

DETAILED DESCRIPTION

Before the present disclosure is described in greater detail, it should be noted that where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics.

Referring to FIGS. 3, 4 and 7, a first embodiment of a dual action sander according to the disclosure includes a housing 2, a rotating unit 3, a driving unit 4, a balancer shaft 5, an engaging member 6, a control rod unit 7 and a sanding disc 8.

The housing 2 surrounds a first axis (L1) and defines a housing space 20 therein that has opposite open ends along the first axis (L1).

The rotating unit 3 is disposed in the housing space 20 of the housing 2, and includes a motor shaft balancer 31 and a bearing 32.

The motor shaft balancer 31 is received in the housing space 20, is rotatable relative to the housing 2 about the first axis (L1), and has a balancer portion 311 and a motor shaft portion 312. The balancer portion 311 defines a receiving space 310 that extends along a second axis (L2) which is parallel to and spaced apart from the first axis (L1). The motor shaft portion 312 extends from the balancer portion 311 along the first axis (L1), and defines a through hole 313 that extends along the first axis (L1) and that is spatially communicated with the receiving space 310. The bearing 32 is fittingly received in the receiving space 310 of the balancer portion 311 and surrounds the second axis (L2).

The driving unit 4 is disposed in the housing space 20 of the housing 2, and is connected to the motor shaft portion 312 of the motor shaft balancer 31 of the rotating unit 3 for driving the rotation of the motor shaft balancer 31 about the first axis (L1). In the present embodiment, the driving unit 4 is a pneumatic cylinder. However, in other variations of the embodiment, the driving unit 4 may be a motor which is also capable of driving the rotation of the motor shaft balancer 31.

Referring to FIGS. 4, 5 and 7, the balancer shaft 5 extends into the receiving space 310 of the motor shaft balancer 31, and is co-rotatable with the motor shaft balancer 31 about the first axis (L1).

Specifically, the balancer shaft 5 has a base segment 51, and a shaft segment 52 that extends from the base segment 51 along the second axis (L2). The bearing 32 of the rotating unit 3 is sleeved on the shaft segment 52 such that the shaft segment 52 is disposed in the receiving space 310 of the motor shaft balancer 31. The shaft segment 52 of the balancer shaft 5 has a mounting protrusion 521 that is not surrounded by the bearing 32 and that has a non-circular cross section. In the present embodiment, the mounting protrusion 521 has a hexagonal cross section, is formed with a fastening hole 520, and is provided with an internal thread surrounding the fastening hole 520.

The engaging member 6 is mounted to the balancer shaft 5. In the present embodiment, the engaging member 6 has a non-circular mounting hole 61 which has a hexagonal cross section, and a plurality of positioning slots 62 which are spaced apart from the mounting hole 61.

The mounting hole 61 extends along the second axis (L2) and is engaged fittingly with the mounting protrusion 521 of the shaft segment 52 of the balancer shaft 5 such that the engaging member 6 is co-rotatable with the balancer shaft 5. The positioning slots 62 surround the mounting hole 61 and are spaced apart from each other. In the present embodiment, the balancer shaft 5 and the engaging member 6 are fastened securely together by a fastening member 9 that extends through the mounting hole 61 into the fastening hole 520 and that is threadedly engaged with the internal thread of the mounting protrusion 521. Specifically, the engaging member 6 further has an inner surface 63 that surrounds the second axis (L2) and that defines the mounting hole 61, an outer surface 64 that is opposite to the inner surface 63, and a connecting surface 68 that interconnects the inner and outer surfaces 63, 64. The positioning slots 62 of the engaging member 6 are formed in the connecting surface 68 and extend outwardly through the outer surface 64. However, in other variations of the embodiment, the engaging member may have just one positioning slot 62, or the positioning slots 62 of the engaging member 6 may only be formed in the connecting surface 68 and not extend outwardly through the outer surface 64.

It should be noted that the cross section of the mounting protrusion 521 and the mounting hole 61 may have different shapes, such as triangle, rectangle, polygon and quincunx, as long as they can be fittingly engaged with each other to enable the co-rotation of the balancer shaft 5 and the engaging member 6.

Referring to FIG. 6, in a variation of the first embodiment, the mounting protrusion 521 is not formed with the fastening hole 520, and the cross sections of the mounting protrusion 521 and the mounting hole 61 are circular. The mounting protrusion 521 is provided with an external thread. The inner surface 63 of the mounting hole 61 is provided with an internal thread that is engaged threadedly with the external thread of the mounting protrusion 521 of the balancer shaft 5 such that the engaging member 6 and the balancer shaft 5 are securely and co-rotatably connected together without the fastening member 9.

Referring to FIGS. 4 and 7, the control rod unit 7 extends along the first axis (L1) through the through hole 313 of the motor shaft portion 312 of the motor shaft balancer 31, and includes a first rod 71 and a second rod 72. The first and second rods 71, 72 are resiliently connected together along the first axis (L1) such that the first rod 71 is operable to bias the second rod 72 along the first axis (L1). Specifically, the first and second rods 71, 72 are connected by a resilient member such that when the first rod 71 is driven to push the second rod 72 toward the engaging member 6, the resilient member serves as a buffer to prevent deformation of the control rod unit 7 resulting from any excessive or abruptly-applied forces. In the present embodiment, the second rod 72 has a circular cross section. However, the cross section of the second rod 72 may have different shapes, or the first rod 71 may be omitted and the control rod unit 7 may only include the second rod 72 that extends all the way through both ends of the through hole 313.

The sanding disc 8 is removably mounted to the base segment 51 of the balancer shaft 5 and is co-rotatable with the balancer shaft 5.

Referring to FIGS. 7 and 8, by virtue of the above-mentioned configurations, the control rod unit 7 is movable along the first axis (L1), relative to the motor shaft balancer 31 of the rotating unit 3, between a locked position and an unlocked position.

When the control rod unit 7 is in the locked position (see FIG. 8), the control rod unit 7 is secured to the balancer shaft 5. More specifically, the first rod 71 of the control rod unit 7 is driven to push the second rod 72 of the control rod unit 7 toward the engaging member 6 in a manner that the second rod 72 extends into one of the positioning slots 62 of the engaging member 6 to be engaged with the engaging member 6, and to prevent the engaging member 6 from rotating relative to the motor shaft balancer 31 and rotating about the second axis (L2). Since the balancer shaft 5 is co-rotatably engaged with the engaging member 6, the balancer shaft 5 is also not permitted to rotate about the second axis (L2) relative to the motor shaft balancer 31 during the co-rotation of the motor shaft balancer 31 and the balancer shaft 5 about the first axis (L1).

When the control rod unit 7 is in the unlocked position (see FIG. 7), the second rod 72 of the control rod unit 7 is separated from the one of the positioning slots 62 of the engaging member 6, such that the control rod unit 7 is disengaged with the balancer shaft 5 and that the balancer shaft 5 is permitted to rotate about the second axis (L2) relative to the motor shaft balancer 31 during the co-rotation of the motor shaft balancer 31 and the balancer shaft 5 about the first axis (L1).

By virtue of the engaging member 6, a proper engagement between the control rod unit 7 and the balancer shaft 5 is ensured. This provides a manufacturer or a designer the room of adjustment to increase a sanding or cutting force of the dual action sander by increasing a distance between the first and second axes (L1, L2). Moreover, since the balancer shaft 5 and the changing member 6 are co-rotatable about the second axis (L2) when the control rod unit 7 is in the unlocked position, the radial arrangement of the positioning slots 62 allows the control rod unit 7 to be operable to be engaged precisely with one of the positioning slots 62.

Referring to FIGS. 9, 10 and 11, a second embodiment of the dual action sander according to the disclosure is similar to the first embodiment. The differences of the two embodiments are described as follows.

In the second embodiment, the mounting protrusion 521 of the shaft segment 52 of the balancer shaft 5 has a non-circular cross section, and the engaging member 6 is mounted co-movably to the control rod unit 7 and is formed with the mounting hole 61 which is non-circular and which extend along the second axis (L2) Specifically, the engaging member 6 has a connecting portion 65 and a sleeve portion 66. The connecting portion 65 is fixedly sleeved on the second rod 72 of the control rod unit 7 so that the engaging member 6 is co-movable with the control rod unit 7. The sleeve portion 66 extends transversely from the connecting portion 65, and is formed with the mounting hole 61 that extends along the second axis (L2) to be fittingly engaged with the mounting protrusion 521 of the balancer shaft 5. In the present embodiment, the cross sections of the mounting protrusion 521 and the mounting hole 61 are both hexagonal.

When the control rod unit 7 is in the locked position (see FIG. 11), the engaging member 6 is driven by the second rod 72 of the control rod unit 7 to move toward the balancer shaft 5 such that the mounting hole 61 of the engaging member 6 is engaged fittingly with the mounting protrusion 521 of the balancer shaft 5. Thus, the balancer shaft 5 and the control rod unit 7 are secured together, and the balancer shaft 5 is not permitted to rotate about the second axis (L2) during the co-rotation of the motor shaft balancer 31 and the balancer shaft 5.

When the control rod unit 7 is in the unlocked position (see FIG. 10), the engaging member 6 is driven by the second rod 72 of the control rod unit 7 to move away from the balancer shaft 5 such that the mounting hole 61 of the engaging member 6 is separated from the mounting protrusion 521 of the balancer shaft 5, allowing the balancer shaft 5 to be rotatable about the second axis (L2). By virtue of such configurations, the engaging member 6 in the second embodiment provides the same function as in the first embodiment.

Referring to FIGS. 12, 13 and 14, a third embodiment of the dual action sander according to the disclosure is similar to the first embodiment. The differences of the two embodiments are described as follows.

In the third embodiment, the shaft segment 52 of the balancer shaft 5 is formed with an elongated recess 522 that is exposed from the bearing 32 of the rotating unit 3.

The engaging member 6 is mounted in the motor shaft portion 312 of the motor shaft balancer 31 and is formed with the mounting hole 61. The mounting hole 61 has a non-circular cross section, is eccentric from the first axis (L1), and is in spatial communication with the receiving space 310.

The control rod unit 7 has an eccentric portion 721 that has a non-circular cross section. The eccentric portion 721 of the control rod unit 7 is eccentric from the first axis (L1), extends through the mounting hole 61 of the engaging member 6, and is movable relative to the engaging member 6 during the movement of the control rod unit 7 between the locked position and the unlocked position.

When the control rod unit 7 is in the locked position (see FIG. 14), the control rod unit 7 is driven to move toward the balancer shaft 5, and the eccentric portion 721 of the control rod unit 7 extends into the recess 522 of the shaft segment 52 of the balancer shaft 5 to be engaged with the balancer shaft 5.

When the control rod unit 7 is in the unlocked position (see FIG. 13), the control rod unit 7 is driven to move away from the balancer shaft 5, and the eccentric portion 721 of the control rod unit 7 is separated from the recess 522 of the shaft segment 52 of the balancer shaft 5.

In summary, the engaging member 6 allows proper engagement between the control rod unit 7 and the balancer shaft 5 when the control rod unit 7 is in the locked position. This provides the manufacturer or designer the flexibility to adjust the configurations of the dual action sander, in order to achieve a greater sanding or cutting force.

In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. It should also be appreciated that reference throughout this specification to “one embodiment,” “an embodiment,” an embodiment with an indication of an ordinal number and so forth means that a particular feature, structure, or characteristic may be included in the practice of the disclosure. It should be further appreciated that in the description, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects, and that one or more features or specific details from one embodiment may be practiced together with one or more features or specific details from another embodiment, where appropriate, in the practice of the disclosure. While the disclosure has been described in connection with what are considered the exemplary embodiments, it is understood that this disclosure is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements. 

What is claimed is:
 1. A dual action sander comprising: a housing; a rotating unit disposed in said housing, and including a motor shaft balancer that is rotatable relative to said housing about a first axis, and that has a balancer portion defining a receiving space that extends along a second axis which is parallel to and spaced apart from the first axis, and a motor shaft portion extending from said balancer portion along the first axis, and defining a through hole that extends along the first axis and that is spatially communicated with said receiving space; a driving unit disposed in said housing for driving the rotation of said motor shaft balancer about the first axis; a balancer shaft extending into said receiving space of said motor shaft balancer, and being co-rotatable with said motor shaft balancer about the first axis; a control rod unit extending along the first axis through said through hole of said motor shaft portion of said motor shaft balancer, and being movable along the first axis between a locked position, where said control rod unit is secured to said balancer shaft so that said balancer shaft is not permitted to rotate about the second axis, and an unlocked position, where said control rod unit is separated from said balancer shaft so that said balancer shaft is permitted to rotate about the second axis; and an engaging member mounted to one of said balancer shaft and said control rod unit, and engaged with the other one of said balancer shaft and said control rod unit when said control rod unit is in the locked position.
 2. The dual action sander as claimed in claim 1, wherein: said balancer shaft has a base segment and a shaft segment extending from said base segment along the second axis and disposed in said receiving space of said motor shaft balancer; and said rotating unit further includes a bearing received in said receiving space and sleeved on said shaft segment of said balancer shaft.
 3. The dual action sander as claimed in claim 2, wherein: said shaft segment of said balancer shaft has a mounting protrusion that is not surrounded by said bearing and that has a non-circular cross section; said engaging member has a non-circular mounting hole that extends along the second axis and that is engaged fittingly with said mounting protrusion of said shaft segment of said balancer shaft such that said engaging member is co-rotatable with said balancer shaft, and at least one positioning slot that is spaced apart from said mounting hole; when said control rod unit is in the locked position, said control rod unit extends into said at least one positioning slot of said engaging member to be engaged with said engaging member; and when said control rod unit is in the unlocked position, said control rod unit is separated from said at least one positioning slot of said engaging member.
 4. The dual action sander as claimed in claim 3, wherein said engaging member has an inner surface surrounding the second axis and defining said mounting hole, an outer surface opposite to said inner surface, and a connecting surface interconnecting said inner and outer surfaces, said at least one positioning slot of said engaging member being formed in said connecting surface and extending outwardly through said outer surface.
 5. The dual action sander as claimed in claim 4, wherein said engaging member is formed with a plurality of said positioning slots surrounding said mounting hole and spaced apart from each other.
 6. The dual action sander as claimed in claim 2, wherein: said shaft segment of said balancer shaft has a mounting protrusion that is not surrounded by said bearing and that is provided with an external thread; said engaging member has an inner surface that defines a mounting hole extending along the second axis, and that is provided with an internal thread engaged threadedly with said external thread of said mounting protrusion of said shaft segment of said balancer shaft such that said engaging member is co-rotatable with said balancer shaft, and at least one positioning slot that is spaced apart from said mounting hole; when said control rod unit is in the locked position, said control rod unit extends into said at least one positioning slot of said engaging member to be engaged with said engaging member; and when said control rod unit is in the unlocked position, said control rod unit is separated from said at least one positioning slot of said engaging member.
 7. The dual action sander as claimed in claim 2, wherein: said shaft segment of said balancer shaft has a mounting protrusion that is not surrounded by said bearing and that has a non-circular cross section; said engaging member is mounted co-movably to said control rod unit, and is formed with a non-circular mounting hole that extends along the second axis; when said control rod unit is in the locked position, said mounting hole is engaged fittingly with said mounting protrusion of said shaft segment of said balancer shaft; and when said control rod unit is in the unlocked position, said mounting protrusion is disengaged from said mounting hole.
 8. The dual action sander as claimed in claim 2, wherein: said shaft segment of said balancer shaft is formed with an elongated recess that is exposed from said bearing; said engaging member is mounted in said motor shaft portion of said motor shaft balancer and is formed with a non-circular mounting hole that is eccentric from the first axis and that is in spatial communication with said receiving space; said control rod unit has an eccentric portion that has a non-circular cross section, that is eccentric from the first axis, that extends through said mounting hole of said engaging member, and that is movable relative to said engaging member; when said control rod unit is in the locked position, said eccentric portion of said control rod unit extends into said recess of said shaft segment to be engaged with said shaft segment; and when said control rod unit is in the unlocked position, said eccentric portion of said control rod unit is separated from said recess.
 9. The dual action sander as claimed in claim 1, wherein said control rod unit includes a first rod and a second rod resiliently connected to said first rod along the first axis, said first rod being operable to bias said second rod along the first axis. 